The mutual interactions between a structural transition and a ferroelectric transition are analyzed for different strain states in a pseudocubic ͑100͒ SrTiO 3 film by examining the equilibrium solutions of the total free energy as a function of polarization, strain and structural order parameter. The range of possible ferroelectric transition temperatures and the possible ferroelectric states of a strained SrTiO 3 film are determined with respect to the variation in the reported properties of bulk SrTiO 3 single crystals. The ferroelectric and structural domain morphologies at a biaxial tensile strain e 0 = 0.94% were predicted using phase-field simulations. It is shown that variations in the reported values of bulk properties and in the Landau energy coefficients from different literature sources lead not only to a wide range of possible transition temperatures at a given strain, but also to different ferroelectric states ͑e.g., polarization along the pseudocubic ͗110͘ vs ͗100͘ directions͒ thus different domain structures under a biaxial tensile strain. Both optical second harmonic generation and confocal scanning optical microscopy measurements demonstrate that the domain states in SrTiO 3 films strained at e 0 = 0.94% and 1.16% exhibit polar directions along the pseudocubic ͗110͘ directions within the pseudocubic ͑001͒ plane of the film.

We demonstrate the dramatic effect of film thickness on the ferroelectric phase transition temperature Tc in strained BaTiO3 films grown on SrTiO3 substrates. Using variable-temperature ultraviolet Raman spectroscopy enables measuring Tc in films as thin as 1.6 nm, and a film thickness variation from 1.6 to 10 nm leads to Tc tuning from 70 to about 925 K. Raman data are consistent with synchrotron x-ray scattering results, which indicate the presence of 180 degrees domains below Tc, and thermodynamic phase-field model calculations of Tc as a function of thickness.

Effect of Pt bottom electrode texture selection on the tetragonality and physical properties of Ba0.8Sr0.2TiO3 thin films produced by pulsed laser deposition J. Appl. Phys. 112, 044105 (2012) Relationship between dielectric coefficient and Urbach tail width of hydrogenated amorphous germanium carbon alloy films Appl. Phys. Lett. 101, 042109 (2012) Interfacial oxide re-growth in thin film metal oxide III-V semiconductor systems A single-domain thermodynamic theory is employed to predict the spontaneous polarizations of ͑001͒ c , ͑101͒ c , and ͑111͒ c oriented epitaxial BiFeO 3 thin films grown on dissimilar substrates. The effects of various substrate-induced strains on the spontaneous polarization were studied. The dependences of the spontaneous polarization on film orientations and the types of substrate-induced strains were analyzed.